Oscillation generator



Jan. 6, 1931. c. J. YOUNG 1,788,362

. OSCILLAIION GENERATOR Filed March 18. 1927 law [i m W2 25 -45 M L L 25 Jr fa k Mm :g. m: 1

Inventor: Char-lea dyoung HLs Attoi -ne Patented Jan. 6, 19311 "3TH: STA S EN r erraarns :r, YOUNG, or sonnnnoranr, NEW-YORK, ASSIGNOR T0 eEnERAL ELECTRIC, 1r

COMPANY, A CORPORATION or NEW YORK Y osoILLAtrron GENERATOR Application mammals, 1927. Serial no. 176,472.,

My invention relates to oscillation generators, and particularly to oscillation generators of the polyphase type. It has for itspurpose, among others, to provide an oscillation generator of this type in which the frequency of the oscillations produced is readily variable. It has for its further purpose to )rovide an oscillation enerator which is adapted for the generation of polyphase currents of audio frequency in a more efiicient andsatisfactory manner than has heretofore been possible and'in which the audio channelsare free from resonant 0r tuned circuits.

. Thenovel features of my invention are set forth in the appended claims. My invention itself, however, both as to its organization 7 and method of operation, together with fur vice 1.

ther objects and advantages thereof, may be best understood by reference to the following descr ption taken in conectlon with the accompanying drawingfwhich illustrates an oscillation tion.

Referring to the drawing, 1 represents an electron discharge device which may be of the three element type which Iemployas a generator of single phase osclllating currents. 2 represents an oscillatory circuit connected between the grid and the cathode 3 the usual feed-back coil which is connected between the anode andjcathode' and whichis inductively associated with the inductance of the oscillatory circuit 2. 1 represents a variable condenser connected in parallel with the oscillatory circuit 2 and which is used for the purpose of adjusting the frequency of the oscillator tOL-dGSlIBd values. 5 represents asecond electron discharge device which I- employ as an amplifier for the oscillations produced by the device 1. This device has its grid connected bya conductor 6 to the oscillatory circuit of the de- The cathodes of theseelectron discharge devices are supplied with heating currents through conductors 7 leading to a suitable source of potential 8. The anode potential for the oscillation generator 1 is supplied by means of a source of potential 9 through a circuit leading from one side of the cathode circuit 7 through the source 9,

generator embodying my inven-,

conductor 10, radio frequency" choke '11, feed-back coil 3, and stabilizing resistance to the anode of the device 1. Likewise the anode potential for the amplifier 5 is supplied by means of the source 9 through a circuit including the conductor 10,radio frequency choke'12, conductor 13, branch ci'r c-uits l4 and 15"to the anode of thedevicefil Connected in parallel with the circuitld is a third branch circuit 16. The branch circuits 14, 15 and 16 comprise theoutputcircuitof amplifier '5 and are made up of in ductance, capacity and resistance of such values as to pass currents bearing a' definite polyphase relation to each other. I Thus, in the particular case shown the current which passes through the circuit16 may lead the current flowing through the circuit 15 by degrees, hereas that flowing through the circuit ltwill lag behind that flowing in the circuit 15 by 60 degrees. Connected in each of these circuits respectively are the primary Thus,-it may be seen that tion of the secondary windingsofthese trans formers with respect to eachother as conventionally shown in the drawing symmetrwindings of transformers 17, 18 and 19.

by properconnec- I rically related polyphase electromotive forces are prod'uced in the secondary windings. It v will, of course, be understood that there may be'as many circuits 14, 15 and 16 as it is desired to have phases inthe polyphase currents which are to be produced. 20, 21 and 22 areelectron discharge devices whichl employ as modulators. The cathodes of these devices'are heated from the cathode circuit 7 and the grids of each of these devices are biased to anegative potential with respect to their respective'cathodes by means of asource of potential 23 which is connected in the circuit leadingfrom the oathode circuit 7 through the source 23, conduc tor 24, 'secondary'winding of the'trans former 25, the secondary winding of the transformers 17, 18 and 19 to the grids of the devices 20, 21 and 22, respectively. 26 represents a second oscillation generator which is connected in a circuit similar to that of the device 1 and having its oscillatory circuit provided with the variable condenser at for the purpose of adjusting the frequency. Connected to the oscillatory circuit of the device 26 is a conductor 27 leading-to the grid of an amplifier 28. The anode of the oscillation generator 26 is connected to the anode conductor 10 through a radio frequency choke 29, and likewise the anode of the amplifier 28'is connected through the primary winding to the transformer and choke coil 49 tozthe conductor 10 both :ofsaid anodes being supplied Withpotential from :the source 9. Condensers 4:6 and conhasits secondarywinding connected in the grid circuit of the modulators 20, 21 and 22 as'has been explained above,

It may thusbeseen that the grids of the modulator tubes2Q, 21' and 22 are impressed with polyphase voltages from the secondary windings of the transformer 17, 18 and 19 and also with single phase voltages from the secondary winding of transformer 25.

The output circuits of the modulators 20, 21 and 22 are connected through reactance-s 30, 31 and 32 .to the primary of the three phase transformer 33. it; will benoticedffrom the ,drawing'that the transformer 33 has six 'primary'w'indings, two disposed upon each leg of a threephase core. These'windings areconnected in a three phase Y. connection two windings upon separate legs of the output transformer being connected in series in each phase 'of the Y. The anode potential for the modulators :20, 21 and 22 is supplied from a source of potential. 35 which is connected between the cathode circuit 7 and the neutral conductor 34: of the Y. The primary coils upon each respective leg of the trans former'33 are so connected that the direct currents flowing through them produce opposing magneto motive forces in the core. Thus the current flowing in the anode circuit of the device21 will flow from cathode conductors 7 through the source 35., conductor 34, primary winding'35 in a direction to pro duce a fluxas indicated by the arrow, pri-L mary 36, reactance 31.130 the anode of the de-. vice 21. Likewisecurrentflowing in the anode circuit of the modulator 20 will flow from cathode conductors 7 through the source 35, conductor 34, primary winding 37, primary winding 38 in a direction to produce a flux as indicated by -the,arrow, reactance 30 to the anode of the device 20. It will be noticed that the magneto motive forces produced by current flowing in the windings 35 and 38 are in opposed relation. By this means the direct current flux in each'of the legs of the transformer is neutralized thus increasing the transformer reactance and enabling a smaller transformer to beemployed. This connection also has the effect of eliminating single ph'asecomponentswhich appearin the outputcircuits of the modulators and alsocertain of the harmonic frequencies. For the purpose of further eliminating harmonics and other undesirable components, including currents having the frequencies of the oscillators 1 and 2, a filter is provided in'theoutput circuit of the modulators which comprises'the above mentioned reactances 30, 31 and 32connected in series with each of the polyphase conductors and condensers 39, .40, 4 1, 42, 13 and 4.4 connected between each f the polyphase conductors of the output .circuit and the cathode conductors 7. These condensers and reactances' are so arranged as to form .a suitable and well known type of filter circuit between the modulators and the primary of the output transformer. Alternativedesigns of filter may of course be used.

In the operation of my device as a genera- .tor of polyphase currentso-f audio frequency I adjust the frequency of theoscillator 1 by means of the condenser d at some definite value. This value is preferably ini the'radio frequency range. I then adjust the frequency of the oscillation generator 2.6'2at a value differing from that of the generator 1 by the 3 frequency of theoscillations which are to be produced; The frequency of this latter generator maybe varied throughout any desired range by means of the condenser 4". Both of these frequencies are supplied to the polyphase circuit including ,the grids of themOdulators 20,21'and22. Thus'hoth single phase and polyphase currentsappear in this circuit. Inithe output circuit of the modulators 20, 21 and 22 appear, among others, polyphase currents having a frequency equal to the beat frequency between the currents produced by the oscillation generators'1 and '26, and also currents having the sllm frequency of these two currents, Preferably in varying the frequency-of the oscillations produced in the output circuit thevfreqnency of the oscillation generator 1 is left constant and that of the generator 2 6'is varied by means of the condenser 4. By this means currents flowing in the phase-splitting circuits let, 15 and 16 are of constant radio frequency thus-enabling an effective splitting of the phases at all frequencies of the output current and by means of inductance and capacity used in threse circuits which are of constant value and comp arable in size with those of the usual radio frequency channel. Since there are no tuned or resonant circuits in the output circuit of the modulators 20, 21 and 22 the frequency of the output currents flowing 'therei'n'may readily-b9 Varied by adjusting the single condenser 4". a I I Thus it may be seen that Lhave produced an oscillation generator of the .polyphase type in which, among other advantages, the output circuit is free from tuned or reso circuits, in which the phase splittingreircuit may be left in one condition throughout the entire frequoncy range and in Which'the frequencymay be readily :varied. Furthermore, it may be seen that my generator-is adapted to the generation of polyphase audio currents, and While I particularly mention its utility in that connection, it will, of course,

he understood that .itisbyno means limited thereto since it is also adapted to the genera tion of currents hayingzfrequenciesthrough? out the frequency spectrum. As is Well understood in the art currents having a frequencyequal to the sum of the frequenciesof the currents flowingin :the .gridcircuit of the modulator tubes will appear in-the output circuit as Well as those of the difference fre quency, and I Wish it to be understood that the generation of currents of the sum fre-' of the modulators will be Va fed in a manner Well-known in the art, and Which need not be here described.

What I claim as new and desire to secure by Letters Patent of the United States, is L 1. In a generator of polyphase currents of adjustable frequency, a polyphase circuit adapted to be supplied With polyphase currents of constant frequency and single phase currents of adjustable frequency, means associated with said polyphase circuit for producing polyphase currents having a I frequency equal to the beat frequency between said polyphase currents and said single phase currents and means for eliminating from the output of said generator currents having a frequency equal to or greater than the lower frequency of the mentioned single phase and polyphase currents.

2. In a generator of polyphase currents of adjustable frequency, a polyphase circuit adapted to be supplied With polyphase currents of constant frequency and single phase currents of adjustable frequency, modulating means for said currents connected in each phase of said polyphase circuit, each of said constant frequency on said polyphase circuit,

means for impressing single phase currents of adjustable frequency on i said polyphase c ir'cuit, modulators associated with said poly phase circuit forprod-ucinga beat note hetWeenT-said.singl ,phase and polyphaseeurQ rents and means for sep aratingsaid beat :note from undesired components including, said polyphase currents ofoonstant frequency.

sle lnia generator of polyphase currents .offadjustabie frequency, a generator of sins lev phase currents of I constant frequency having :an outputicircuit, means 1n said output gcircuir -or conuentingsaid single phase currents into :polyphase current-an polyphase circuit having said 'polypliase currents impressed thereon, a second generatoriof single phase currents; :of adjustable frequency .nieansfor impressing said single phase cu rents upon each phase of said polyphase circuit,.modulating means adaptedto be sup;-

plied with currentfrom ,said polyphase circuit'tand means for eliminatingundesired componentsincludingcurrents of said co'n- "stant frequency from the output currents of said modulating means, I 5. I n-Ya polyphase ioscillatien generator, a generator of -:single phase oscillating ourrents ihavin r an output circuit, means ins-aid output circuit ferconizerting said sing'le phaseicurrents into ,fpolyphase circuit having said poly-phase currents impressed thereon, a 'second gener'ator of single phase oscillating currents of frequency: differing from the frequency of said polyphase cur-rents, means for impressing 'said singfle ipha'se' currents upon each phase ofsaid ipolyphase circuit, means connected in eac'hphase offsaid polyphasecirouit for modulating1said currents and means for eliminating'fromiithe output of said-modulating means curren'ts' 'of frequ'ency greater than .th at ofccurrents produced by summer said generators; I

polyp hase ourrents, a :9

so i

6. In aipolyphase oscillation generator, a

generator of single having anoutput cireui tcomprisinga plurality of fbranches,'said branches being adapted to conduct currents 'havi ng a desired phase relation, a 'polyphase circuit, each phase of said polyphase circuit having current imzpressed thereon from acorresponding branch of said output circuit, a second generator of single phase oscillating currents'of frequency di fleringfrom the frequency of thementloned osclllatlng currents, means for impressing said single phase currents upon each phase of said ipolyphasecircuit, vacuum 'tube gmodulators associated With said polyphase circuit and means associated with *the output CIICUItSOLfSaId modulators for cancelling the tor.

single phase components of said first generaphaseoscillating-currents generator of a single phaseoscillating cur- "rents, anloutput-circuit for said-single phase generator,including a plurality o'f 'branches,

said branches being adapted tocondu ct cur-i rents having a difinite phase'relation, a polyphase circuit, eachphase of said polyphase circuit having current impressed thereon from a corresponding one of said branches, means for impressing currents of'a frequency differingby amounts within the'audio range from said polyphase curr'entsupon said poly- 7 phase circuit, means rm varying the free quency of currents impressed on said circuit by said last means, and means associated with said polyphase circuit for producing polyphase currents havinga frequency equal to the difference between the frequencies of said two currents.

8. In a' polyphase oscillation generator,a generator of single phase oscillating currents, an output circuit for said single phase generator including a plurality of branches,saidbranches being adapted to conduct currents having a difinite phase relation, a polyphase V circuit, each phase of said polyphase circuit being associated with a corresponding one of said branches and adapted to beimpressed with current therefrom, means for impressing single phase currents of frequency differing by amounts within the audio range from said polyphase currents upon said polyphase circuit, means for varying the frequency of currents supplied by said last means, and

cuit, each of said modulators having ananode, a polyphase transformerhaving a pluralityof primary windings on each leg and an anodeconnection for each of said modulators including a winding on each ofaplurality of legs of said transformer whereby undesired current components are "eliminated, l 11. In combination, a generator of single phase oscillations of constant frequency, a polyphase circuit, means for producing polyphase oscillations from said single phase oscillations and supplying said polyphaseoscillations to said circuit, a second generator of single phase oscillations of frequency differing from said polyphase oscillations by an amount within the audio range, means for varying the frequency of oscillations'produced by said second generator,.and means associated with said polyphase circuit for producing polyphase oscillations having a] modulating means associated with said polyphase circuit. a p

"9. In a polyphase oscillation generator, a

plurality of single phase radio frequency oscillation generators which differ invfrequency by an amount within the audio range, one of said radio frequency oscillation generators having an output; circuit comprising a plurality of branches, said branches being adapted to conduct currents of desired phase relation,ia polyphase circuit, each phase of which is supplied with current from a corresponding branch of said output circuit, means for supplying single phase current from another of said generators to said polyphase circuit, a plurality of electron discharge modulators for producing a beat frequency between said currents, each of said modulators having a grid and anode which are-connected in one phase of said polyphase: circuit and means connected in the anode circuit of said modu- I lators for separating currents of said beat frequency from the radio frequency componcuts of the output from said modulators.

10. In combination, a generator of single phase current of constant frequency having an output circuit, :means in said output cir cuit for converting said single phase current into polyphase currents, a polyphase circuit having said polyphase currents impressed thereon, means for supplying single phase current to each phase of said polyphase circuit, an electron discharge modulator for I said single phase and polyphase currents connected in each phase of said polyphase, cir- 

